The invention concerns a fuel-injection arrangement for a combustor of a gasturbine engine, and in particular a fuel-injection arrangement enabling reliable performance at low load conditions of said engine.
Provision is made in gas turbine engines to inject fuel into a region upstream of the main combustor region of the engine for mixing with air and eventual burning in the main combustor region.
FIG. 1 shows part of a gas-turbine engine comprising a combustion chamber 10, a fuel-inlet head 12 and a radial swirler 14 disposed therebetween. The swirler 14, which is commonly used in gas turbine engines as a mixing device to mix fuel and air for supply to the combustion chamber, is configured as illustrated in FIGS. 2a and 2b and comprises a series of vanes 16 equally spaced around a circumference of the swirler, the vanes forming a corresponding series of passageways 18 for the flow of mixing air 20 through the swirler from a radially outer to a radially inner region thereof.
The vanes are shaped and disposed such as to impart to the incoming air a tangential component, whereby the air is caused to "swirl" around the longitudinal axis 22 of the swirler, the air also being caused to exit the swirler at a downstream region thereof and enter the combustion chamber 10 (see arrows 21).
Along the trailing-edge region 24 of the vanes 16--i.e. trailing-edge in terms of air flow through the vane arrangement--are conventionally disposed a series of fuel outlets 26 fed from a fuel inlet conduit 28 connected to the fuel head 12. The outlets or holes 26 are of uniform diameter and are evenly spaced axially along the trailing edge. Use of such holes evenly spaced along at least most of the length of the trailing edge promotes better mixing of fuel and air by making for a uniform distribution of the fuel along the axial length of the swirler.